1. Field of the Invention
The present invention relates to a low-noise level internal combustion engine, and more particularly to an internal combustion engine having means for suppressing engine noise at a considerably low level.
2. Description of the Prior Art
In order to suppress engine noise, there have been proposed two ways: one is to enclose the entire of the engine proper with a soundproof board with projected parts, such as intake and exhaust tubes, fuel supply tube and electric wiring, being exposed to the outside through openings formed in the board, and the other is to cover the lower portion of an engine room of a vehicle.
However, these ways have drawbacks in that in the former way, the entire construction of the engine is bulky and the heat radiation from the engine is poor because the heat emitted from the engine surface is compelled to stay within the engine enclosing soundproof board, and in the latter way, sufficient noise blocking is not achieved because of difficulty in covering the lower portion of the engine room due to obstructions of the steering and suspension parts which are located at that lower portion.